Desiderium
by Indulgence-Ahoy
Summary: In a flash he was gone. (Underswap and Underfell alternate universes)
1. Fallen

Chapter 1

 _In which a promise is broken._

"Paps!" shouted Blue from the bottom of the stairs. This ritual was as daily as rituals got: A) Wake up Paps in plenty of time to get ready to go to work. B) Wake up Paps -again- in time to get some breakfast before going to work and C) Yell at him from the bottom of the stairs until he finally dragged his bony body out of bed, into the kitchen and, be somewhat-not-so-late to work.

You would think that for a monster who could just teleport to work, being late would be a non-issue. Blue suspected that his brother liked to see how far he could push it: " _Just a second to go? HA! I can be there in half a second!"_

He also seemed to need to be really annoying about it.

Maybe it was a big brother thing.

Not that Blue minded all that much, of course. It was just part of his day. Nothing that the Sensational Sans couldn't handle.

However, that particular day he couldn't help impatiently tapping the tip of his fingers on the wall next to the stairs. He had so much to do that day! Plans for a brand-new puzzle at the bridge between the Ruins and Snowdin were finally done. He really hoped he could get to building it before his own sentry shift started.

"PAAAAAAPPPPS!" he shouted again. He wanted to avoid going into his brother's bedroom just in case Papyrus was planning into tricking him into a tickle/pillow/sandal/possibly all three fight.

He would win, of course, but he simply didn't have the time!

To his delight, he saw his brother's room door open and soon after a -mostly- awake Papyrus yawned and stretched into view.

"I'm UP" He declared even though he looked like he was ready to be anything but that.

"Paps! I woke you up 2 hours ago!" admonished Blue crossing his arms.

"You did?" said Papyrus with one raised eye ridge as he made his way downstairs "Must've decided to sleep on it"

Blue groaned but his smile stayed. "You're lucky that I'm here to wake you up every morning, otherwise you would sleep the rest of your life away! Today is a perfect day to get stuff done!"

Papyrus side glanced at the nearest window. Snowdin was its usual grey, snowy and cold self. What passed for a "perfect" day here was a day without a snowstorm.

"I think I would be ok with that" he commented with a smirk.

"That's not a good way to think Paps" said Blue heading into the kitchen "You can't possibly want to sleep all day. I mean, who could?"

"Sounds like a challenge" said Papyrus following his little brother.

"Paps…." sighed Blue

"Fine, fine, I'll take on this challenge another day" chuckled Papyrus sitting at the kitchen table. He saw the meal that Blue had already prepared for him, along with his usual cup of coffee with 5 spoons worth of honey. Just the way he liked it. He felt a faint twinge of guilt at not helping his brother out more with these types of chores. Ideally, he should be making breakfast for his little brother at least occasionally. He used to cook all the time when Blue was too young to use the stove.

Well, he heated up stuff in the microwave. _If one wanted to be honest about it._

Him and being able to make edible, homemade food was one of those things that were never meant to be. Even Undyne had declared it impossible. She showed him the scientific formula that proved it and everything.

Blue sat across from him with his own sugary cup of tea.

"I may be late coming home" he said with a grin "I'm starting construction on the bridge puzzle"

"OH?" It occurred to Papyrus he should be offering to help with this project but … "So… "

"Soooo I may be late tonight" repeated Blue grinning "I'm planning to work on it before my shift and, afterwards if the weather holds up. Don't worry, I already made dinner and put it in the fridge."

Blue was letting him off the hook. He appreciated this gesture on his little brother's part and wanted to return the favor. "Ok. Ummm… How about if I make dinner tomorrow?"

Blue put his mug down slowly and stared at him with big blue eyes. "Yeah?"

 _Oh shit. He's calling my bluff._

"Really?"

 _Damn. He's doing the sparkly eyes._

"You mean it?"

… "Yes"

"Thank you for offering Paps, but I don't think we can afford to replace the stove again" giggled Blue.

 _Phew._

"Hm. Thank you for the vote of confidence" fake scoffed Papyrus. HE wasn't going to let his little bro get away with this teasing, even if, well, it was based on truth.

"Aw! C'mon Paps, I'm joking! Do you really want to make dinner tomorrow?" said Blue trying to hide his apprehension by collecting his mug and other dirty dishes from the table.

"Nye, he, he! Well, how about Take Out? My treat"

"Oooooooh! Ok!" said Blue looking a little relieved. Maybe a little more than he intended. "But now it's time for work!"

It was Papyrus turn to groan.

They teleported to the bridge and said their goodbyes. Blue had arranged it with Alphys so his sentry shift didn't start until noon that day. Alphys was only too happy to oblige. She loved Blue's fighting spirit but she had confided in Papyrus that she worried that Blue never took any time off. Working on puzzles may not technically be "time off" but at least it meant him doing something other than sitting inside a small wood cabin most of the day, or training with her.

" _Even a warrior needs to learn to enjoy peace"_

She was right but nobody could ever force Blue to do anything that he did not want to do.

Papyrus crossed the bridge and waved at his little brother. Blue waved back happily as he held a hammer with his other hand. "I love you! See you soon!" he shouted merrily.

As he walked over to his usual sentry spot. Papyrus decided that he would do some business that day so he could get a little extra gold for tomorrow. Blue's excitement was contagious. Maybe instead of their usual Muffet's fare, he would take Blue to the Capital for dinner. That was sure to surprise him.

Suddenly he didn't feel as sleepy and felt readier for the day as he made more and more plans. He and his brother hadn't hung out in quite a while.

Blue was right, today was a perfect day to get things done.

Papyrus woke up to the feeling of a small hand touching the top of his skull.

"BLUE!" he exclaimed rubbing his eye sockets to clear his vision from the dried traces of tears. "YOU'RE HERE!"

"Hey, hey, nah" he heard the small skeleton say with a worried tone "I'm not Blue"

Papyrus realized that the skeleton next to him was Red. _Why was Red there? Where was he?_ He brought up his legs and clumsily scrambled into a sitting position. He squinted at the room and soon remembered that he had laid down on the living room sofa at Red and Fell's insistence.

"Stretch?" he heard Red ask with a voice that sounded so much like his brother's even if a few decibels lower "You ok?"

Papyrus stared at him as his brain collected more of his scrambled memories.

"Aaah …. Aahh… how many da … where …. Where…" He looked around the room looking for the answer his soul did not want confirmed.

Red sighed.

"It's been a week" he answered with a grimace, grinding his teeth before continuing on. "It's been a week …. Since your bro disappeared"

Papyrus blinked at him then got up and started making his way to the door.

"Stretch! Hey!" exclaimed Red trying to grab for his arm but was shoved out of the way. "FINE! Don't listen to me!" Papyrus had been about to reach the door when his soul felt heavy and, his body was lifted into the air and slammed back onto the couch.

"Your Undyne said you needed to REST!" growled Red.

Papyrus struggled against Red's soul magic, surprising the small skeleton with his erratic strength. "Calm the fuck DOWN!" said Red releasing Papyrus' soul and grabbing for his arms instead "Boss is out there looking for him along with your friends. You almost keeled over from lack of sleep yesterday, 'member?"

Papyrus stopped suddenly and managed a scraggly "sorry".

He remembered now.

His brother had not come home that day.

Papyrus had gone searching for him that night into the next day. The puzzle at the bridge showed signs of having been worked on for several hours and the tools had been put neatly away in Blue's backpack. Which was left resting against one of the anchoring beams. The only thing that had been missing was the hammer Papyrus had seen his little brother holding when they had separated.

That night's search had yielded no clues. Snowfall had covered any tracks that might've been left behind.

Alphys and Undyne had received a frantic call in the early hours of the next day. There had been some speculation that maybe Blue had decided to camp out in the forest without letting his brother know. Incredibly irresponsible and therefore, un-Blue like, behavior. BUT possible nonetheless.

Everybody had been sure that Blue would turn up soon.

Then the second day came to a close.

Papyrus traveled to Underfell in the hopes that Blue had decided to go visit their counterparts there without notice. A _gain, why would he do that?_ But at that point Papyrus was willing to forgive anything.

Blue had not been there either, and after seeing Papyrus' state, Red had decided to come back to Underswap with him to kick Blue's butt help out. Fell had decided to come too since he was worried too had nothing else to do that night.

Then a third and, a fourth day had gone by.

The Fell brothers traveled back and forth between their worlds every day. "To keep an eyes on things". To any outsider it was obvious that it was more to keep an eye on "Stretch" (their nickname for Papyrus)

The unspoken worry had been that Blue had fallen off the bridge. It wasn't very high up, but enough to seriously injure any monster unfortunate enough to drop from there. Blue was sturdy, but his HP was still 1. If he had been injured … if he had spent all those nights exposed to the elements …. If … if …

The royal guard dogs had found no traces of monster dust.

Good news in a sea of dread.

It was on the fifth day that Stretch had passed out while they were looking through another area of the forest. It was on this same day that the Fell brothers had decided to extend their stay in Underswap.

" _That fool can't even take care of himself"_

And now, back in the present, the only thought in Stretch's head was that it hadn't been a dream. Blue was still gone.

"Hey, you hungry?" he heard Red say quietly. "I made some hot dogs and …."

The door opened and Fell came in brushing snow off his scarf. Stretch and Red looked at him expectantly.

Fell shook his head in response to their looks, then lifted his left hand to show the hammer that Stretch had last seen Blue using.

"Where…?" croaked Stretch.

"A short way from the bridge, in a part of the forest off the path" Fell said somberly "It was inside a crevice. One of your guards stumbled upon it" Fell had probably been ready to add how this wouldn't had been overlooked under his watch but he decided to be merciful. "We … didn't find anything else. Nothing tangible, at least"

"Tangible?" asked Red

"Your dogs …." started Fell. He paused as he looked for the right words "said that there were many weird smells"

"Weird … smells" repeated Stretch

"They said they had never smelled monsters like that" Fell gave Stretch and his brother a long look. "Nor magic like that"

"Fell… what are you saying…" said Stretch getting up. A haunted look in his eyes.

"Whatever happened to your brother … to Blue. I don't believe it was not his choice" said Fell keeping his eyes on his Underswap twin. Pity dancing at the edge of his hard stare "Bad, corrupted magic was involved. Your Undyne is looking into this… There is not….. WAIT!"

Papyrus teleported out of the house. He appeared next to the bridge wheezing in response at the sudden change in temperature and magic pull. He looked around orienting himself and spotted a set of lights down the path into the forest. He teleported again and ended up next to the trees that bordered the spot Fell had mentioned. Through their trunks he could see Undyne and Alphys speaking to each other as another couple of monsters used some instruments to scan the area.

He burst through the trees startling them both and almost getting an axe in the eye in return.

"PAPYRUS!" admonished Alphys in a tone he had heard Blue use many times. "WHAT ARE YOU DOING HERE?"

"Fell … Fell said Blue was here" explained Papyrus eyeing the axe blade barely a couple of inches from his face. He turned to Undyne with hopeful eyes.

Undyne looked away. She played with a strand of her long red hair before answering. "Paps… Look…. I mean, y-yeah, there is a high possibility that Blue was here, but…"

She pointed at the instrument she had been showing Alphys. Papyrus recognized the device from his lab days, as a basic magic energy detector. "All - All that's left in this area is some faint traces of some unidentifiable magic, and, and they are … troubling"

"What is it?" asked Papyrus. Fell's words came to him … _Bad … Corrupted_

Undyne chewed on her lower lip. "I - I only seen magic signals like these once before. The tra - traces are very faint, mind you, but…" Undyne stopped and sighed gathering her courage. "Paps, these are the traces of magic from fallen monsters"

Papyrus opened his mouth and took a step back. His whole body starting shaking.

"W-wait, Wait!" said Undyne reaching for his arm "I said, MonsTERS. Plural. And these traces are not your brother's blue magic. The only reason we think he was here, it's because of that tool we found and - and because" She pointed to a few blast marks on the nearby trees. Papyrus recognized them right away.

"Bone attacks" he said.

"Right" confirmed Undyne.

"Undyne…" implored Papyrus "What happened? Where … where did Blue go?"

Undyne exchanged looks with Alphys.

"I- I'm sorry Paps" she said "I don't know…"

They held Blue's funeral a year later.


	2. Rejected

Chapter 2  
 _In which things have changed_

Fell was not the type of monster that startled easily. He was the kind that startled - no - _frightened_ \- the living heck out of anything that dared approach him without his consent. Woe be to that monster or mythical human. They would not live to repeat such a mistake!

Therefore, Stretch hadn't startled him that morning. Stars, no. He had meant to spill his coffee all over the counter.

 _Ahem._

Despite the fact that Stretch had been coming to Underfell for morning practice for a couple of weeks by now, Fell was still not used to someone who got up before he did. Much less someone who could just teleport into his kitchen at any goddamn time. Yeah, ok, his own brother Sans could teleport as well, but he was never awake before Fell and, he knew damn well to not do it in such a careless manner.

"You ok?" asked Stretch lazily watching the coffee spill spread across the counter.

"I have told you before to not just teleport inside my house" reprimanded Fell "You are supposed to wait for me at your designated place"

"I did" Stretch shrugged his shoulders "Got bored. Ran a few laps but, got bored again"

"Hm" commented Fell. He eyed the kitchen clock. It was barely 5 minutes after 5 a.m. He glared at Stretch "Have you slept at all?"

Stretch looked everywhere except at Fell "I have … _unless you mean in the last 48 hours_ " He added quickly.

Fell growled. "You know DAMN well that Royal Guard needs to be alert! What good are you if you are falling asleep at your post?"

"You know I don't need that much sleep, Fell" he said defensively "I'd rather be moving"

Fell sighed. Under any - _any_ \- other circumstances he would find this admirable.

"FINE. If you fall asleep during our training, I'm throwing you back into your world and our deal is off" he said walking out of the kitchen.

By now, some of the coffee spill had began splattering to the floor. "What about …." called out Stretch pointing at the growing mess.

"Red will take care of that WHEN HE GETS HIS LAZY ASS UP!" yelled Fell up the stairs towards Sans' bedroom door. "SANS! YOU BETTER BE UP AND READY BY THE TIME WE GET BACK!"

Stretch tapped his foot impatiently. Red was a grown up, he shouldn't be counting on his brother to wake him up on time.

"SANS!" repeated Fell.

There was some noise from the smaller skeleton's bedroom then something that sounded like a mumbled "i'm up, i'm up"

Fell hmmm'd to himself and turned to leave. As he did so, he noticed Stretch rolling his eyes.

"Let's go" he growled to his Underswap twin.

After he heard the door close, Red poked his head out of his bedroom. He rubbed his eye sockets and yawned. He hadn't gotten much rest last night, despite having been too exhausted to even change into his sleeping clothes. His mind had been busy giving him restless dreams.

His eyes fell upon the empty living room and the now eerily quiet house. It was much too early to deal with anything and, normally he would've just gone back to sleep, but now that Stretch was coming over three times a week to train with his brother, his stress levels had gone through the roof. And that was saying something because it wasn't like he had had any real peace ever since Blue had disappeared into thin air.

He couldn't believe it had been a little over a year since that day. He _missed_ Blue, more than he could ever admit. They were close in a way that was different from anyone else.. Like Fell and Stretch, Blue and him were "dimensional twins" (a name coined by Blue, which just went to prove that it was good that he didn't get to name a lot of things). Their personalities couldn't be more opposite if they tried, but they understood each other. They both were extremely loyal to their brothers and were the last of their kind in their corresponding dimensions-universes-timelines, _whatever_. Red was still deciding what their worlds actually were.

There were as many differences between their worlds as there were similarities. Magic didn't work quite the same way in Underfell as it did in Underswap. It required a lot more effort and, unless the monster was skilled, it tended to be chaotic. Most monsters in Underfell bore scars from being too careless with magic. Heck, the healed crack over his left eye was proof of this.

This whole arrangement ... it was all … _very weird_.

None of this would've happened if he hadn't been tinkering around with the machine left behind by the former owner of the house.

Red was no scientist, but he could understand most machines if he had enough time with them. _MOST_. The one currently residing in the back room of their home was still a mystery to him. It would probably stay that way. All he knew about it is that once he got it working (somehow) it had opened a portal to another version of their own world. A world which had alternate versions of everybody he knew. Heck, they even had their own version of the same machine. Same dents and everything.

Their first meeting had been tense, for that matter … many of the follow up meetings had been as well. It had taken some back and forth between the two pairs of brothers before they became used to each other. And much more than that before they were on friendly terms. Well, for Fell to be on _friendly_ terms with Stretch. Because as usual, Blue had just adopted everyone from day one, and Stretch and Red had come to terms fairly quickly.

Blue had suggested at one point, that there were probably a lot of other worlds out there with their own machines. Maybe one day they'd be able to go visit them. Red had just nodded dismissively at this notion. As far as he knew this machine was a one-time-direct-connection deal.

Stretch had had his own ideas regarding the machine, and other worlds, and many other things. Their conversations had been fascinating. Blue may have been his twin but Stretch was certainly more attuned to his interests.

He … He was a friend. A close one.

At least, at one point they had been.

Now Red wasn't so sure anymore.

Ever since that dark day Stretch had just changed.

They still talked.

But It just wasn't the same.

 _Goddammit Blue_. Sighed Red. _Where hell are you?_

.

..

…

" _HE'S NOT DEAD!" screamed Stretch. The painful growl behind the statement resonating deep inside Red's chest._

 _Fell did not even flinch. He had obviously been expecting this reaction from Stretch. How could he expect anything different? He had just stated that after all this time of searching, the only reason they hadn't found Blue was because he had to be dead._

 _Still, Red couldn't believe Fell had said it so … so easily. He looked around the Underswap living room where Fell had asked them all to gather. The three of them along with that world's Undyne and Alphys. The females looked just as shocked as Stretch, but they were probably reacting more to the statement than the painful truth behind it._

 _It had been a year since Blue left. They had combed that Forest for most of that time. The search had even included other areas of the Underground, including the Ruins. There had been no clues, no new leads. No hope._

 _Stretch had become obsessed. He would go off on his own and they would not hear from him for days. Returning exhausted and, in some cases, with unexplained injuries._

 _How many times had his Alphys argued with him regarding his actions? How many times had Red taken it upon himself to patch him up with Undyne's help. How many times had his own brother, also gone on his own searches?_

 _The only reason Red didn't follow suit was because he had been prohibited … no … practically begged by Fell to not do so. Fell had said that Red just wouldn't be able to handle it. Red would usually just ignore him and go off on his own, but the way Fell had said it..._

 _He had sounded desperate._

 _And now, he was saying to Blue's closest friends that they should stop searching and let go. Let go of Blue._

 _Stretch had slammed Fell into the wall and proceeded to punch him several times in the face._

" _STRETCH!" yelled Red and tried to grab Stretch's soul to stop him. To his surprise, Stretch resisted his hold and sent a large femur bone his way, hitting him on the arm. Fell was on Stretch in the next instant punching him in return._

" _LEAVE HIM OUT OF THIS!"_

 _Undyne helped Red get up and checked on his injury. Luckily it was minor as there had been no killing intention behind it. More than the pain, Red was still reeling from the shock that Stretch had turned on him so easily._

" _A-ALPHYS! DO SOMETHING!" yelled Undyne "THEY ARE G-GOING T-TO KI-KILL EACH OTHER!"_

 _Red watch Underswap's Alphys stand before them as she watched the fight closely. Her large, powerful frame was something that he still hadn't gotten used to. His own world's version of Alphys was smaller and you would certainly never find her close to a fight as fierce as this one._

" _I will … " she said "if it gets serious"_

" _HOW CAN YOU NOT THINK IT'S SERIOUS?!" argued Red_

" _Have you noticed that Fell is not using any of his powers?" said Alphys' over her shoulder._

 _Red blinked and looked at the two of them exchanging punches and throwing each other all over the large room. While it was true that some furniture would need to be fixed, neither of them were using magic and most of the damage, so far had been contained to just themselves. Either of them could've ended this fight easily using blasters or, a well placed bone attack. Perhaps the only reason Stretch had used magic at all had been because Red had used it in the first place._

" _Stretch needs this" said Alphys somberly._

" _What the h-..." commented Red_

" _Language" said Alphys not even looking away from the fight._

 _The sound of bone cracking._

" _Not yet" said Alphys._

 _A table splintered against the wall to their collective left._

" _Just give them a few more minutes"_

 _A Gaster blast missed their heads by just a few inches._

" _ALPHYS!" yelled Red and Undyne in unison._

" _Ok. Ok!" said Alphys sighing and quickly making her way to the fighting pair. It had taken a couple of slaps to the back of their heads and the threat of limbs becoming separated from their bodies before the partial destruction of the Underswap brother's home came to an end._

 _Both Fell and Stretch lay on the carpeted floor panting. Fell got up first and adjusted his battered scarf back into place. Stretch then got up and, while glaring at Fell, repositioned his broken finger, making everyone but Fell wince in sympathy._

" _If you're THAT serious about fighting" said Fell applying green magic to some of his injuries "You should train under me. I can help you find the monsters that … "_

" _FUCK OFF" said Stretch teleporting away._

 _Fell sneered at the empty spot. "He needs a collar"_

 _Red came over. "Boss, want me to go after him?"_

" _No, he'll come back. He just needs to -think- about it" said Fell then, as if he had not noticed it before, he looked around the half destroyed room "He DOES have potential"_

 _Alphys and Undyne both started speaking but Red beat them to the question that was on both of their minds "Boss, why did you provoke him like that? You don't really think that his brother is dead, do you?"_

 _Fell busied himself with his gloves before answering._

" _Blue had training. He was resourceful. He could be annoying sometimes but, none of us can't say that he lacked determination" he said finally. He looked at each of them in turn "If he could come back, he would've done so by now. This ... uncertainty is -killing- that fool of an older brother"_

 _Nobody could really disagree. It was something each of them had thought about at least once, if not more._

" _This needs to stop"_

 _._

 _.._

…

 _Stretch had not stayed away for long after his fight with Fell and, when asked again had not voiced anything against having the ceremony._

" _Do what you want" was his only comment._

 _The funeral itself had been a modest affair despite the entire town being present. The Fell brothers stayed in the background, mostly to keep an eye on the stubbornly quiet Stretch. When asked for a few words, he declined._

 _Everyone not in his immediate circle looked at him with pity. Everyone was aware that the Underground held its own set of dangers. As far as anyone else knew, it had been an accidental death. Poor, poor dear._

 _At the small gathering afterwards, Red noticed Stretch try to sneak off into the woods behind the brother's house. He started following when he was stopped by Fell's hand on his shoulder._

" _Boss?" asked Red._

 _Fell sighed and let go of his shoulder then turned away from him. Confused but determined to not let Stretch go off on his own -again- the small skeleton made his way through a group of monsters, and soon he was just a few paces behind the taller skeleton._

 _Stretch stopped at the river and rummaged for something inside his jacket. Finally, he pulled some cigarettes and a lighter._

 _It occurred to Red that he hadn't seen Stretch smoke since that day. He waited a little while but Stretch just stood there looking at the items on his hands as if he didn't recognize them. Red cleared his throat to announce his presence._

" _Hey" said Red walking to Stretch's right side. When he didn't receive a response he balanced his weight on his heels and looked around "At least it's not snowing, huh?"_

" _Hm" said Stretch._

 _*Well that was stupid* Thought Red. *Why was he there anyway?. What could he possibly say?*_

" _Huh, uh, just came over to … to…" he looked at Stretch's hand "To see if I could bum one off you" he finished pointing at the cigarettes._

 _Red was nowhere near as much of a smoker as Stretch was. Most of the time, he only did it when he and Stretch went fishing together. It was a habit too much of a bother and too expensive to keep up._

 _Stretch gave the entire pack of cigarettes and lighter to Red without a word._

" _Uh … ok. Just wanted one" mumbled Red then took one out of the package and after placing it in between his teeth, he lighted it. He took a couple of puffs and exhaled slowly. He sneaked a look at Stretch only to discover that the taller skeleton had been staring at him the entire time. "What?"_

" _Nothing" said Stretch then after a long pause he added "You shouldn't smoke"_

" _What? Seriously?" said Red managing a small smile "You. Are. Telling. ME. I shouldn't smoke"_

" _Yeah. I'm telling you that" said Stretch but he looked away towards the calm river in front of them._

 _Red stubbornly kept the cigarette in his mouth. He offered the rest of the package and lighter back by holding them out on his hand, but he was ignored._

 _*Isn't this lovely* He thought looking around and, trying really hard not to look as uncomfortable as he felt. He exhaled more smoke and flicked a few ashes from the tip of his cigarette._

 _Suddenly, the package and lighter were snatched from his hand and thrown into the river. Red turned to Stretch, dumbfounded._

" _You shouldn't smoke" growled Stretch not looking at him._

 _Red glared at him but still removed the cigarette from his mouth and put it out in the snowbank next to him._

" _Fine" he said quietly._

 _They stood in silence for about half an hour. Red's legs started bothering him and he fought the urge to sit down on the snow. "Look…." He started. "This whole situation …" he waved his hand in front of him vaguely …."Sucks"_

 _No response._

 _Red sniffed and adjusted his jacket. The Underground light was dimming. It was getting significantly colder._

" _Maybe we should head back. Before we freeze in place" said Red. When he was, again, ignored. He reached out and grabbed Stretch's arm "Ah, C'mon"_

" _Will you just… stop?" said Stretch not moving an inch._

" _Stop what?" said Red blushing._

" _Stop trying to be my buddy"_

" _YOUR WHAT?" exclaimed Red "I'm just trying …. I don't know … Help you?"_

" _Don't" said Stretch turning away from him. "Stop trying. Stop trying like your brother wants everyone to do. Go back to your backwards world and leave us alone"_

" _Aaargh. Don't tempt me!" Red rubbed both sides of his skull in frustration "But … but, I can't!"_

" _You can't" repeated Stretch looking at him over his shoulder._

" _Blue wouldn't do that. I can't do that. You know your bro would've stuck by us … if … if… something happened to me or boss" Red avoided Stretch's gaze_

" _I can't" he said again defeated. He was in no mood to suddenly get all confessional. Couldn't Stretch just let him help without the need for an interrogation._

 _He saw Stretch turn his body back to face him out of the corner of his eye. He didn't dare to look up at him._

" _You're not my brother" he heard Stretch say resentfully. Red felt his HP drop a bit. "You don't need to pretend to be him"_

" _Huh?" said Red as Stretch turned to return to his house. "Yeah, well, I WOULD NEVER WANT TO BE BLUE WITH SUCH A DUMBASS FOR A BROTHER!"_

 _Stretch's long strides soon took him out of view. Red stayed a little bit longer. His legs refusing to move. It wasn't until the light had almost completely gone out before he started walking back. His jacket's sleeves wet from tears._

.

..

…

A short while later he had learned that Stretch had accepted Fell's offer to train him. He had announced to the group that was still at his home that he would catch and bring the monsters that had taken his brother away to justice.

Alphys had been a little taken aback by the announcement but had eventually agreed that if Stretch was able to pass the trials coming up in three months, she would consider giving him a Cadet position in the Royal Guard. In the end, Red guessed, she may have just been glad that Stretch seemed to be moving away from the self destructive behavior he had been indulging in lately.

Red and Stretch hadn't talked since then. It had only been a couple of weeks, but still.

Red honestly didn't know what to do. He had tried to help out by making food for both Papyruses and keeping both houses organized and clean among his other duties as a Sentry. He never thought of himself as the domestic type but it felt like it was the only thing he _could_ do.

For some reason he could not figure out, Stretch resented him.

What else could he do? He just couldn't do _nothing._

Blue wouldn't.

No. What Blue would or could have done did not matter. At least, Stretch was right about that.

The problem was in …

Did it matter at all what Red did.


	3. Gift

Chapter 3  
 _In which Stretch learns new things. Fell thinks he knows things and, Red is just so over others assuming things._

There weren't a lot of things that impressed Fell.

This is a lie.

There were actually quite a few things that impressed him but,few of those he would openly admit to Underfell wasn't the kind of place where one could spend a lot of time being impressed. Not if you didn't want to get dusted while marveling at how impressed you were.

So in the pursuit of honesty, let's say that there weren't many things that made him go "wow". Therefore, you can imagine just how annoyed he was with himself that he had just added a new one:

Stretch had amazing dodging skills.

He'd never had all of his attacks register as a MISS before. Fell's Underswap counterpart didn't even seem to be trying too hard either. Stretch was just kinda there one moment, then just enough out of the way of the attack the next. He could at least have the decency to not look like he was about to fall asleep.

The only other monster that came close to this sort of skill was his own brother Sans and, this had been only after years of training under him. Fell knew how to pull his punches with Sans while still being a threat. He may not have had the intention to kill his brother but, 1 HP was still 1 HP. A badly aimed bone attack could injure him badly enough to weaken his soul to the point of falling. Fell's control over his magic was legendary and, the main reason why he was the current Captain of the Royal Guard.

However, he didn't have to worry about hurting Stretch too much. He had HP to spare. His ATTK and stamina left much to be desired, however. Fell wondered how he had manage to become a Sentry to begin with with such horrible stats. Blue probably had something to do with that, since their Alphys, who was Captain of the Royal Guard in their world - unbelievable as this was- seemed to be particularly fond of him.

Fell studied his foe as he prepared to launch another attack. Stretch stood in a ready stance but his face had a faraway look. He almost looked _bored._

Fell, however, knew better. He may not understand how another version of his world, of himself, could exist -Much less such a gratingly opposite version- but, what he did understand, deep in his soul was that regardless of all the differences they shared, they both cared deeply for their siblings.

But more so, Stretch was hurting.

Death was a common occurrence in Underfell. At least much more so than in Underswap. Everyone Fell knew had at least lost one family member, friend or ally. Fighting between monster gangs was something that happened often in his world. Fatal magic usage was another reason. Magic was just that unpredictable there. That's why Royal Guard members had to be so much tougher and skilled than anyone else. They were the only ones keeping their world from completely tearing itself up between violence and sheer stupidity.

Snowdin had been especially dangerous until he became the Royal Guard Captain. His new title had allowed him to put a leash on the local dog gangs that used to . Nobody would ever - _ever_ \- dare to mess with the skeleton brothers. Sans may not have his title nor look the part, but he could defend himself effectively if he needed to. That was the only reason Fell had no problems with Sans holding a Sentry position.

That is … until Blue disappeared.

Fell could understand … even _accept_ being dusted in the line of duty. Fell knew that Blue took his obligations and training seriously. He was an incredibly capable fighter for someone that looked like he could be dusted with a mere mean glance.

 _Fell had been the one who suggested they spar -as a joke- Blue complied by excitedly summoning a barrage of blue and white bones, surprising the Underfell guard. Up to that point, Fell had suspected that everyone in Underswap fought by having really aggressive tea parties._

 _And, after a couple of rounds of attacks, his surprise evolved into shock when he suddenly found himself being confronted by an annoyed Blue._

" _Are you serious?" Blue had asked. His eyes were big and bright and he was still smiling, but there had been an edge to his voice that Fell couldn't ignore. He instinctively knew what Blue was referring to. Fell had been toning his attacks down out of habit. "It's not nice to lie, Fell. If we're going to fight, let's fight!"_

 _Fell smiled. -Ok. Then-_

 _Their fight escalated from that point on. Fell no longer felt the need to hold back. Blue could handle his attacks and give back just as good. Well -almost- as good._

 _He needed some work. He tended to lean too much to his right and liked to show off by spelling attack names with the bones. "Celestial Punch!" (Really?) Spelling anything with bones may indicate exceptional control but it was also a tremendous waste of energy._

 _It was very obvious to Fell that there wasn't a shred of killing intention in Blue's offensive maneuvers. His bones were always blunt, not sharpened like Fell's red ones. And Blue had a preference for aiming at limbs rather than the soul. Gathering all these facts along with years of experience soon gave Fell the upper hand. He ended the fight with a well placed hit to the jaw which left Blue seeing stars and with a small bone scar._

 _Blue was proud of this scar and had to practically wrestle Stretch away to keep him from healing it, the moment he had seen it on his brother's face._

 _That had been the first spar of many._

 _Blue was a quick learner and Fell found himself on the defensive quite a few times, but the small skeleton never changed his position on fighting without killing. He wasn't above cracking the random kneecap or dislocating shoulders. He always followed up with green magic though or healing items, but he never apologized._

 _And Fell respected that._

Whomever took him was still out there and, they had no idea who or what it was. A year may have passed without any other incidents being reported but still, until they were sure, Fell couldn't risk it.

Fell missed Blue, but he could only phantom the depth of Stretch's sorrow. It was something he never wanted to find out. This whole demeanor. This whole "I only care for justice for my brother, nothing else" attitude.

This was a lie.

"It's not nice to lie, Stretch" murmured Fell.

"Um… what?" asked Stretch snapping back from whatever daydream he had been having. Three giant red bones manifested to his right, left and back, forcing him forward. "WOAH!"

"It's time to get serious" announced Fell a giant red blaster skull appearing behind him.

When the pair returned to the Underfell home, the last thing Red expected to hear coming from them was laughter. The small skeleton had just finished putting breakfast on the table when they came in. He turned off the stove and peeked out of the kitchen to see Stretch gesturing wildly at his older brother.

"What do you mean you haven't named him?!" he was asking "That fantastic beast deserves a name!"

"It's a weapon. A magical manifestation. It does NOT need a name" argued Fell, although Red could tell that he was enjoying Stretch's compliments.

Red guessed they were talking about Fell's Gaster Blaster. That had been a fairly recent development for the Underfell brothers and Red was still trying to figure out how to - if it was at all possible for him - manifest one. It surprised him that Fell had decided to show off like that. The Blaster had been declared a "super secret weapon" after all. The air quotes had been seriously emphasized.

"Bah!" commented Stretch "You're no fun". He turned around and saw Red looking at him from the kitchen. He looked away suddenly self conscious, his smile vanishing from his eyes.

"Uh … yeah" said Red "Boss is very practical about stuff like that, ha, ha" He scratched his chin nervously and gestured toward the kitchen "Welp, better eat up, I'm sure we're all very busy and such"

By then Stretch had learned better than to refuse Red's cooked food. It just wasn't worth the argument with Fell and to be fair, Red was a pretty good cook. It had not gone unnoticed to the tall skeleton that Red had toned down the spiciness in his food ever since Stretch started having breakfast there. Not that he had complained.

 _He didn't think he complained. Did he?_

"Yeah, ok" Stretch said walking towards the kitchen.

Fell cleared his throat surprising Red. "Sans, I need to talk to you. In private"

Red raised an eye ridge and walked closer to Fell, who motioned him to come outside with him.

Stretch watched them leave with some curiosity but didn't give it much thought.

As he sat down he spotted the steaming cup of coffee and then a jar of honey wrapped in brown paper with a ribbon. Stretch blinked at it a couple of times as his brain registered the implications. He knew sweet honey wasn't easy to come by in Underfell. The local monster bees produced a sour like substance instead. He picked up the container and saw that the label on the cap was from Underswap. Not only that, this was the kind you could only get at the Capital. He remembered mentioning to Red about it once when they were talking about their favorite foods.

There was a rule among both sets of skeleton brothers.

In order to keep the portal machine as discreet as possible, they had agreed that neither would ever venture on their own in their opposite world. Meaning, Stretch wasn't allowed to leave the areas designated by the Fell brothers and, in turn, Red and Fell were not allowed to go beyond the Underswap household without company. This was mainly to prevent any confrontations. Since, while Stretch and Red were more sensible and not prone to unprovoked exploration, Fell was fight happy and, Blue was hug happy. Either of those could end up badly in the wrong world.

That honey meant that Red had gone out into Underswap, traveled to the Capital and bought that expensive honey for him. Neither Fell nor Red cared for sweet stuff.

 _How dare he?_

He got up and lifted the jar over his head with the intention of smashing it but he found himself unable to. He brought it down close to his face. Even Blue had talked about getting some for Stretch's birthday.

His birthday. That had been just a few weeks after that day.

He hadn't even remembered. He suspected that nobody else had wanted to bring it up considering the circumstances. Maybe Red had decided to … get him a gift.

 _He had told him to stop trying to be … his buddy!_

The front door opened and a very sour faced Red entered followed by Fell. The small skeleton noticed Stretch just standing next to the table with a somber face.

"What's wrong now?" he growled but didn't wait for an answer. He took a left started heading for the stairs that led up to the bedrooms.

Stretch chewed on Red's tone for a couple of seconds before remembering he had been mad at something.

"Hey!" he exclaimed. "What the fuck Red? What are you doing going to the Capital?"

Red stopped and turned around slowly. "What the…"

"What are you talking about?" interrupted Fell.

"Your bro here is going to the Underswap Capital without telling us" said Stretch pointing to the jar of honey as if it was all the proof anybody needed.

"I… " started Red

"Sans isn't THAT stupid!" argued Fell "He knows better than to run off by himself in that clusterfuck you call a world!"

"Boss…"

"Fell, he obviously did!" He stomped closer to Fell, so now he was mere inches away from him. "This honey is only available at the Underswap Capital!"

"Sans knows better. even if he did decide to indulge your need for this crap for some FORSAKEN REASON, he knows how to take care of himself!"

"SO DID BLUE!" yelled Stretch.

Silence fell upon the room.

"GeeEEEEEEEZZZZZZ" commented Red "FIRST OF ALL MR DETECTIVE, YOUR ALPHYS GAVE ME THAT TO GIVE TO YOU, SHE FOU…" He looked away flustered "NEVERMIND! WHATEVER THE FUCK IS GOING THROUGH YOUR HEADS, I DON'T CARE! I DON'T NEED THIS! FIRST BOSS IS LAYING ME OFF AND NOW YOU'RE ACCUSING ME OF SNEAKING AROUND LIKE SOME HELPLESS LITTLE KID!"

Red looked back at his brother and Stretch. A faint red flush permeating his skull. "FUCK. BOTH. OF. YOU." He declared before turning around and stomping his way up the stairs and back to his bedroom.

Stretch and Fell watched him in silence until the bedroom door slammed shut, then they both turned to each other.

"WHAT IS WRONG WITH YOU?" they both asked, canceling each other's annoyance.

This time however, Stretch took the initiative by holding one bony index finger up and taking a couple of steps away before speaking again.

"What did Red mean by you laying him off?" he said in a tone he hoped didn't sound like he cared too much.

"It's none of your business" said Fell

"Yeah, well, I still want to know why" said Stretch burying his hands in his hoodie.

Fell sighed. "I dismissed him from his Sentry duties. I told him that I needed him to work on organizing my paperwork since I'm busy TRAINING you! You forget that I am the CAPTAIN OF THE ROYAL GUARD HERE, YOU UNGRATEFUL SWINE"

"Yeah, but lay him off? Isn't being a Sentry like a huge fucking deal with you guys?" said Stretch

"It is"

"So … why?" prodded Stretch "Weren't you just declaring how capable he is with defending himself?"

"My brother is more than capable to handle the job. -I- made sure of that. He can be very lazy but when he gets his mind on something, he gets it done" said Fell in an angry whisper "However …." His voice got even lower "I rather he stayed close to home"

Stretch looked at Fell's impassive face for a long time. "You're scared…." he said finally.

"You don't know what you're talking about" growled Fell.

"I? … I DON'T KNOW WHAT I'M TALKING ABOUT?" said Stretch gesturing to himself, to the jar in his hand, to everything.

"What the fuck is your deal with this?" said Fell snatching the jar of honey and inspecting it. "Why did you automatically assume that my brother had purchased it?"

"BECAUSE THE ONLY OTHER MONSTER WHO KNEW ABOUT THIS BEING MY FAVORITE WAS …." Stretch paused as realization dawned on him. He grabbed the jar again and pulled on the ribbon around its wide neck. A piece of decorative paper had been tied to the end of it and tucked into the brown paper covering. He immediately recognized Blue's scrawly handwriting.

-* HAPPY BIRTHDAY!* -

Don't eat it all in one sitting! I mean it!

-Sensational Sans

Stretch fumbled with the jar as if wanting to let it go but not daring to at the same time. He fell unto his knees staring at it as if it might disappear at any moment.

Fell approached him slowly and took the jar from his trembling hands. He peeked at the note but he had already suspected who it was from. He placed it next to Stretch.

Fell went into the kitchen and saw the toast and tea that Red had prepared for him. He ate a slice of the toast and drank his tea without even sitting down. When he came back into the living room, he found Stretch in the same state he had left him in.

"Make sure to apologize before you return to your world" said Fell somberly. "I don't care if you don't return, but at least be monster enough to do that before you leave. I have matters to attend to"

The Underfell Captain of the Royal Guard exited his home and promptly made his way to his headquarters at the outer edge of Snowdin. On his way, he checked on traps and sentry stations. He yelled at monsters slacking off and even managed to stop two major fights by his mere presence.

Nobody doubted his power.

Everything was running smoothly. Now that his brother was officially off Sentry duty, he could stop having one of his inner circle guards keep an eye on him during his shifts. Nothing had happened these last few months. There had been no reports of any strange monsters prowling the area. No strange occurrences or disappearances. His meetings with Underswap Alphys had yielded the same results.

This was good.

Taking his brother off a position that exposed him to the same, if not more danger, than it did Blue, was the last step in ensuring that things would stay this way.

This made him feel at ease.

This was also a lie.


	4. Plan

Chapter 4

 _In which brothers fail at communicating and Red goes on a trip_

In a few words: Memories can be cruel.

While it is unfair to call something that we keep in our minds such an unkind word, the fact still remains that they can be our worst enemies. They change and devolve as time passes. Sometimes influencing our emotions and our actions, no matter how sure we are of them.

So kindly, they are cruel.

Stretch wasn't sure how long he sat on the floor of the Underfell home's living room, drowning in his. His head was convinced that only a few minutes had passed, while the stiffness in his joints argued that it had been at least an hour, maybe even more. Whatever the case may be, Fell was long gone and the house had been very quiet since then.

It was the type of quietness that invited memories that Stretch had tried hard not to dwell on anymore. It wasn't that Stretch wanted to forget Blue, but remembering that he wasn't around was still a painful, insidious process.

Outside, Stretch could hear random Underfell denizens walk by from time to time. In this world, the skeleton's house was much closer to the border with Waterfall than in Underswap. Then again, there were less homesteads in this version of Snowdin overall. Most Underfell monsters preferred to live in Waterfall and/or Hotland Red had told him. This was due to monsters seeking to live closer to the Core, where magic was stronger and more stable. Up until the skeleton brothers decided to settle there, Snowdin was pretty much a lawless, forgotten town.

" _Anything that happened in Snowdin, died in Snowdin"_

Now it thrived as the first line of defense from a human invasion.

You know, if there ever was one.

The thought of Red reminded Stretch that he wasn't alone in the house. Not unless the younger skeleton had decided to teleport away. He wouldn't blame him if he had, but Stretch felt it in his gut that Red was still sulking around in his room.

Stretch considered his options. He could just leave and pretend like nothing happened. Meet with his Undyne for any news, join Alphys for training and, maybe go home and ...

OR,

He could go upstairs and apologize.

OR….

 _Or…._

Yeah, he should apologize.

He looked over at the jar of honey next to his feet. Resentment niggled at the back of his soul. Even when he wasn't there, he influenced his life somehow. Stretch could've stayed in bed that day. Avoid feeling guilty about not helping with that damned bridge puzzle. He wouldn't have worked late getting money together so they could spend a day together just being bros. Maybe if he had gotten home earlier, he could've gone to meet up with his brother before ...

… _Blue would still be gone. …._

Uninvited.

 _What if Blue had wanted to leave?_

 _If he had felt so overwhelmed with having to take care of his lazy ass brother, then he should've just said so and not pulled this disappearing act!_

 _He always had to be SO dramatic about everything._

Unwanted.

 _... Why won't you come back?..._

Thoughts.

Why did he even have to have a brother? Why? Stretch was never any good to him. As soon as he had been able to, Blue had been the one responsible for taking care of both of them. Stretch was just the occasional money maker. His younger brother could've chosen to live in the Capital with family friends after their father died but noooo, Stretch had insisted they stayed together.

Everything would've been so much better if Stretch had been the one to disappear.

 _...Where did you go?..._

He kicked at the honey jar weakly. He didn't deserve it. He watched it roll across the room and under the couch out of sight. He got up, rubbed the back of his head and sighed in defeat.

"I thought you liked that stuff" he heard Red say. Stretch whipped his head to his right to see the small skeleton standing halfway down the stairs. Overall, Red just looked tired and in a bad mood. His whole body was hunched over making him look even smaller than he was.

"Hey Red" Stretch said. He had intended to follow that up that with _something_ … What could he realistically say that wasn't a lame apology?

When had been the last time he had actually talked to Red? Like really talked to him? He had _said things_ to him, sure, but not in the same way they used to talk all the time.

Red understood his jokes right away and even if he didn't, he laughed anyway. Heck, he even came up with worse jokes that made the taller skeleton groan. A feat that nobody else had ever managed.

But now, Stretch couldn't even look at him for long. Red just looked too much like his younger brother. Maybe a tiny bit taller (and this was debatable, because they had both refused to prove this one way or the other.) his voice was lower and mannerisms were certainly different, but Red just had to say something or… smile in a certain way and there was Blue for a fraction of a second.

All the energy that Stretch had earlier that day was gone. He felt sore and despondent. Certainly not in the mood for a heartfelt conversation. He hung his head until he heard Red reach the bottom of the stairs and walk past him towards the kitchen. Stretch reached out blindly and snatched the hem of Red's sweater.

"What?" Red asked grumpily when he felt the tug. "I'm just going into the kitchen, which last I checked, is still in Underfell and not your precious Capital"

"Sorry" murmured Stretch

"Sorry?" Red took a long step away to free himself from Stretch. "Ok, yeah. Sure. What about?"

Stretch lifted his head and looked at him making Red take another step away. It felt like this was the first time in a long while that Stretch had really looked at him and not just past him.

The tall skeleton opened his mouth to say something but instead he just hm'd to himself in exasperation and looked away again. Why was this so hard?

Red's eye lights dimmed. He wasn't sure what he had expected. "Whatever. Look. I don't care, alright? I tried to but I'm not in the business of being 'all selfless' and 'forgiving' like your bro … was"

"No. You are not" agreed Stretch, his voice lowering with each realization, every breath "I don't know … I don't know how Blue managed to be that way, but … but it's not like I'm expecting YOU to be. I know, **I KNOW** , you are not him"

"Yeah"

"So, I'm sorry, ok?" said Stretch keeping his gaze on the far wall. He was sure he could not look at Red now. Not without embarrassing them both.

"Yeah… ok" said Red and started walking to the kitchen. He put a hand on the archway leading into the kitchen and peered back at Stretch who was still looking away, avoiding him as had become the norm. The usual. The rule.

 _I'm sorry I'm not him._

A few days went by without Red seeing Stretch at all. During that short amount of time, his life changed drastically, even more so than it had the first few weeks following the tragedy, when he had made it a point to check on Stretch every day after his Sentry shifts.

Back then, his brother had insisted that he kept up with his Sentry duties in Underfell regardless of the events in Underswap. Whether to keep up appearances or what, Red didn't know. Fell just wasn't keen on discussing the reasoning behind his decisions. He just expected Red to accept them. On his part, however, Fell had done the opposite of his orders to Red and spent a lot of time in Underswap as he did his own private search for Blue. Back then, Stretch didn't seem to care to have an Underfell monster roaming freely about his world. Maybe he just trusted Fell more, for all Red knew.

Stretch spent a lot of time away from home anyway, between traveling all the different areas of the Underground and the Ruins. There was little to do maintenance wise in the Underswap home. The lanky skeleton didn't cook for himself and most of the food in the fridge had gone to waste. If it hadn't been for his friends vigilance, help and too many times - just plain, sheer luck of a friendly passerby helping out - Stretch would've probably starved or fallen from exhaustion.

After a while, Red became sure that Stretch was no longer searching.

He just didn't want to be home.

Red avoided going into the bedrooms of the Underswap home. He had been in them several times before, neither of the Swap brothers being particularly private about their possessions. Stretch had the same cleaning habits as Red when it came to his personal space: Organized chaos. It may look messy to others, but they knew where everything was in their room and it was comfortable that way. Besides, it drove the corresponding siblings crazy, which was an unspoken plus.

Eventually Red's visits dwindled to maybe twice a month. Juuussstttt to make sure the Underswap home was still standing and the machine that allowed him to travel between worlds was still working properly.

His Sentry work became his focus, and dedicated himself to keeping an ear and eye out for anything that might be of interest to his brother. The Captain's absences had not gone unnoticed, but Fell was always able to explain them away or quell any rumors that may threaten his position. How Fell managed that so easily, was a mystery to Red.

Now,

Red was home all the time. There was no point in going to Underswap. Stretch didn't want him there - that was pretty obvious. When Fell returned that day when Red had been dismissed as a Sentry, he brought a stack of paperwork with him. Mostly patrol reports along with some accounting and puzzle maintenance recordings, that needed to be transcribed from dog speech, categorized and filed into boxes. Boxes which were then sorted and given to a courier monster to take back to Fell. Basically, grunt work. Red had never seen his brother do this "paperwork" himself before, this had probably been some other weak monster's task back at headquarters before it had been assigned to Red.

His questions as to why he had to do it had gone mostly unanswered. Fell tried making it sound like Red was the only monster he trusted to be competent about it, but Red knew his brother better. Fell would have not waited for so long to get someone "competent" to do this if it had been so important, and let's face it, Red was good with numbers but the last monster you would consider for this type of busy work.

Besides, there wasn't enough to keep him occupied all day. He was done in a couple hours most days. The rest of the time he spent on his computer or watching television. It wasn't like Snowdin was a hub of activity and interesting things to do. Even Grillby's didn't get jumping until after dark and even though Fell didn't approve of the place and always had a comment about Red spending time there, he didn't stop him from going.

It had only been a few days, but it felt like years had gone by without anything of consequence happening to the young skeleton. Was it going to be this way the rest of his life?

Maybe ….

Maybe he should follow Blue's example.

He shook his head. _That's stupid._

Yet, everyone was giving up - moving on. Stretch, Fell, _everyone._

He was the only one stuck. The only one that hadn't done _anything about it._

The only one who hadn't been allowed to search for Blue.

So - maybe -

Maybe, just maybe, the reason nobody else had found Blue was because only another Sans could find him.

The more time time did as time does, the more this thought took root in Red's mind. The "what ifs" soon became active planning on his part. The idea of finding out what had happened to Blue, the chance of giving an answer to this mystery when nobody else could, became more and more tantalizing.

He repeated to himself several times that he wasn't going to be gone for long. That if he timed it just "right", Fell wouldn't even notice his absence. His brother was due a meeting with the King soon, meaning he would be gone overnight. If he left right after his brother did and came back early the next day, none would be the wiser.

IF….

If he came back with new clues or even Blue in tow, everyone would be happy and ashamed that they hadn't used his abilities sooner.

If he didn't. Well … his brother would have to find another monster to fill out his paperwork then.

In either case ….

It's not like Red wanted to disappear like Blue did. Not really. He would leave a note, of course.

 _Of course._

.

..

…

Sometimes, Red could hear Stretch and Fell talk and exchange ideas from his bedroom window. He always made sure that his curtains were drawn and that his window was only the littlest bit open. There was no doubt that Stretch was avoiding him. He no longer came into the Underfell home and instead waited for Fell outside, even if it was snowing.

Red gave up on including Stretch in his breakfast preparations. He just prepared a meal for him and Fell and then retreated to his bedroom with the excuse of "having work to do", which also meant that he was spending less and less time with his own brother. Not that Fell seemed especially bothered about this.

Of all the things he had expected to happen after meeting the Underswap brothers, having Stretch and Fell actually get along in such a will-not-kill-you-on-sight manner, was the last thing on his list. From what he could gather from listening to them, was that Stretch had been training really hard, especially on summoning his own gaster blaster. So far, he hadn't managed a fully realized one but he had been close. He sounded eager, even excited. Red never thought he would hear him talk like that again.

Also, from his tone of voice, Red could tell that Fell was actually enjoying this process as well. He bet Fell loved having someone else he didn't have to be "careful" with while training.

Red grunted and looked at the calendar on his bedroom's wall. Only one more day before he got his chance. He then switched his vision to the bag under his bed containing his supplies for this self appointed mission.

He wasn't running away, far from it. He wasn't a crybaby bones.

However, if he didn't come back … well … at least he would leave a note.

He forgot the note.

Well it wasn't so much that he forgot it but more that he ended up not having time to take care of this detail. On the morning he was supposed to leave he had been distracted.

The monsters that showed up at his door didn't give him much choice. Their long arms and claws had been on him in an instant.

The Underfell denizens that walked by the Underfell brother's home later in the day, noticed the door slightly ajar. Some had been curious about it, but knew better than to pry. It was the Royal Guard Captain's house after all, they did not want to risk his wrath.

Let his brother suffer the consequences for being so forgetful.


	5. Parallels

Fell tapped his right foot impatiently. It was only because he was alone that he allowed himself such an obvious show of disrespect towards the King. There was no need for him to do these meetings in person but, he insisted upon it if only to remind everyone in the Royal House that he was the one in charge of their armed forces.

The Golden Hall had seen better days. The metal that gave the place its name was stained and darkened around the edges not for lack of care, - the Royal House was full of monster servants to do the work - but because of the King's influence. His powerful magic had, at one point way before Papyrus and Sans' time, corrupted the entire Underground. The details on what had happened changed depending on whom you asked; the only thing that the older monsters seemed to agree upon was that the Core had been built to help offset his influence and that it had thankfully worked - for the most part. Magic became wild and difficult to master. To the younger monsters, this was just part of everyday life.

Fell wondered what Underfell had been like before the corruption. He guessed that it probably was closer to what Underswap was now. That thought lingered in the back of his mind, bothering him a little more than he cared to admit.

Steps on marble interrupted his thoughts. The King's Liaison was approaching him slowly and purposely. Fell had never seen her before. The previous Liaison had been an elderly dragon that liked to ramble. Perhaps the King had finally decided to dust the old fool.

The new Liaison was a light teal fire Elemental with feminine traits. She wore black robes with red trimming and the seal of the monarchy on their chest. It was very hard to tell age with Elementals but to Fell experienced eyes, she looked like she was too young for a job like this.

"Captain Papyrus?" She asked when she was only few feet away. Her voice had a bit of a crackle behind it and she kept her flames subdued. A sign of respect among Elementals.

"Yes"

"I am Mana" she said quietly. "I sincerely apologize but The King is currently busy with my mentor"

 _An assistant, that explained things._

"It seems that there had been some unusual reports from the Royal Scientists that our King decided to oversee himself" she continued.

Papyrus raised an eye ridge. A sickening feeling sprouting in his soul. "Unusual … reports?"

"Yes, so if you could just hand your survey reports to me. I'll make sure the King gets them as soon as he is …"

"Why wasn't I informed about this?" growled Papyrus as he handed over the envelope with his written reports "As Captain of the Royal Guard I should know about any potential threats to the Kingdom"

"I don't know. I am not privy to the details myself. Perhaps it's just something out of your jurisdiction?" She said, neither her tone or flame wavering, giving Fell a hint as to why she may have been chosen for the job. "I'm sure that not everything that happens at the Capital needs to have the Captain of the Royal Guard involved"

Fell grinded his teeth. "I WOULD LIKE TO SPEAK WITH THE KING, NOW" He commanded.

"I'm sorry, but like I said, the King is currently busy with other matters. Perhaps he will be available tomorrow. Would you like me to pencil you in?"

Fell glared at the fire Elemental. "I AM NOT…."

 ** _"_** ** _CAPTAIN PAPYRUS!"_**

Fell and Mana turned their gaze to see the greater dog guard running into the Golden Hall.

"CAPTAIN PAPYRUS, I HAVE URGENT NEWS" he said, panting as he tried to catch his breath. Fell leaned expectantly but the dog guard eyed the Liaison unsure if he should continue.

The tall skeleton cleared his throat getting the hint. "IF WE ARE ALL DONE HERE, I SHALL GO AND SPEAK WITH MY ASSOCIATE OUTSIDE. THANK YOU FOR YOUR TIME AND PLEASE GIVE THE KING MY REGARDS"

Mana blinked at him confused. "So you don't want me to see if ..."

"I WILL CONTACT THE KING PERSONALLY IF I NEED TO. THANK YOU" said Fell waving his right hand in dismissal and ushering the guard to walk alongside him with his left.

He heard a huff behind him and the sounds of steps walking away from them. He allowed himself to smile briefly before his brain reminded him as to why they been interrupted. Once he made sure they were in an area they wouldn't be overheard, he turned to the guard.

"What is your news?" he asked crossing his arms and keeping his voice low.

"You need to go back to Snowdin, Sir. We received word that your home has been broken into" whispered the guard following his Captain's example.

Fell stared at the guard. The tips of his gloved bony fingers digging into his upper arms.

"When?"

"I'm not sure Sir. Sometime ... yesterday. I was just told to come get you…"

"YESTERDAY? Why am I only being told about this NOW?!" growled Fell, making the guard take a step back and hiding his tail between his knees.

"Sir … the guard posted near your home was dusted. His absence wasn't noticed until this morning"

Fell's soul thumped against his rib cage. He turned on his heel and started walking fast towards the exit startling the Guard. The dog had to practically run to catch up to his superior.

"My brother?" he asked. His pace not slowing down.

"... We haven't been able to find him, Sir"

Fell broke into a full run.

For the Captain of the Guard It had taken too long to get back, even if other monsters would disagree. Nobody had expected him back within a few hours of sending news. Travel between Snowdin and the Capital could take close to a day if everything went ok. The giant chasm between Waterfall and The Core being a huge factor for this. There were monster birds that would fly you across if you had the gold and a flexible sense of survival, since these particular birds were known to lose their 'cargo" terrifyingly often. Otherwise, you had to travel by foot or by river around it, then deal with a steep climb.

However he had managed it, Fell had made it back to Snowdin before dark.

 _Too long._

He remembered the version of the events that he had been told about the day Blue had disappeared. Stretch had waited until night to start the search for him. Nobody had expected Blue to be home earlier than that. Stretch had tried calling his brother but had received no answer, but he hadn't worried. Why would he? Blue tended to get really hyper focused when working on a puzzle. It wasn't out of the realm of possibility that he just hadn't heard his phone buzz.

Later on they found his phone inside the tool bag he left behind. Along with an uneaten lunch.

 _Too many parallels._

Fell looked at his own phone. He had called Red several times with no answer. He ignored the guards that came up to him as he reached his own front door and hit redial for the 20th time. He spun around when he heard a buzz and saw a rabbit guard holding his brother's phone as if he just been caught holding something precious.

"WHERE?" demanded Fell, snatching the phone away.

"Its was on the living room floor, Sir" answered the guard.

Fell's eyes went wide and he opened the door to his house. The remains of furniture and claw marks on the walls immediately giving him hints of the terrible things that had happened. The captain took a long, sharp breath. He felt his hands shaking, so he balled them into fists to hide them.

"Who's out looking?" he asked without turning around. He hoped that the tremor in his voice was only evident to him.

"Patrol 2 is searching the Forest, Sir" reported the guard that had kept his brother's phone "Patrol 1 is rounding up and questioning possible suspects"

"DO NOT LET ANYONE GO BEFORE I INTERROGATE THEM" commanded Fell. He walked further into the living room and started taking stock of where everything was.

"Yes, Sir"

"I'M HOLDING YOU PERSONALLY RESPONSIBLE FOR ANY COMMUNICATIONS FROM PATROL 2. THE MOMENT THEY FIND SOMETHING -ANYTHING- I AM TO BE INFORMED. IS THAT CLEAR?" Fell looked at him over his shoulder. His eyes flashed red.

"Yes .. YES SIR!" stammered the guard and made his way out of the Underfell home barely avoiding slamming himself into the doorway.

As soon as he was left alone, Fell released a shuddering breath. The heaviness in his chest now more evident than before.

 _"_ _Too many parallels"_ he whispered to himself.

 _"_ _What's bugging you now?" asked Fell. Red had been increasingly quiet that day. They had just been in Underswap for the third time._

 _"_ _It's just weird, ok?"_ _Red said._

 _Fell snorted as they exited the room that held the machine that had connected their world to Underswap. An undignified sound he would only emit in front of his brother. Honestly, wasn't it obvious that Underswap was a weird place? What was his brother going to say next? That snow was cold?_

 _"_ _Sans, you are a master at stating the obvious"_

 _"_ _I don't mean that kind of weird, boss" sighed Red as he made sure the door to their storage room was properly locked "What I meant is that it's weird how many parallels there are"_

 _Fell stopped walking and looked at his brother suddenly intrigued. "Parallels?"_

 _"_ _Well, you know … it seems that everything that happens there, eventually happens here. Didn't you notice the calendar in their house? Is off by like a year from ours"_

 _Fell had to give it to his brother. He had not noticed such a thing. He had barely noticed the color of the couch in their goddamned living room._

 _"_ _Are you saying they live in our future?" scoffed Fell._

 _"_ _Nah. Not exactly. It's just that Blue was telling me about how he had been the one to convince Alphys to let Stretch be a Sentry" Red waved his hands as he tried to bring his thoughts together "While here, you were the one to convince Undyne to let me be a Sentry. You know, before you took over her job"_

 _"_ _Ok, but that little blueberry version of you is not the Captain of the Royal Guard in Underswap" said Fell with a sarcastic smile "Not that it would be that HARD"_

 _"_ _I know, I know! That's what I meant by not exactly!" said Red exasperated. He really hated explaining things that made sense in his head "They don't live in a future version of our world or anything like that. It's just that it seems that if something major happens there, there is a good chance that it is going to happen here too, or at least something very similar"_

 _"_ _Pfft"_

 _"_ _Whatever" said Red stomping past Fell and towards their front door._

 _"_ _Tell you what brother" said Fell following him "If you are right, this means we will get advance warning of when humans decide to try and invade us"_

 _Red grunted a noncommittal response._

 _"_ _And you'll be able to know what you are getting for all your birthday gifts"_

 _Red opened the door to their home and rolled his eyes at his brother. "I was just making an observation, alright boss?"_

 _Fell chuckled. "It was a fine observation brother. I just think it's a little out there"_

 _"_ _We just were in an alternate version of our world, making a treaty with monsters that are us in that world, and … and this is what you think is a "little out there""? scoffed Red back._

 _"_ _Fair point" agreed Fell as they entered their home. He made a mental note to notice more of these "parallels". Despite the teasing, he did trust his brother's judgment._

 _Parallels_

When Blue disappeared that word had come back to haunt him. He had dismissed the notion at the beginning especially since Red didn't seem to be particularly worried about it. Looking for their friend was more of a priority then, but as the months passed the dread had come back.

 _"_ _It's just that it seems that if something major happens there, there is a good chance that it is going to happen here too, or at least something very similar"_

Fell ran his hand against the claw marks on the wall. They were big but feral in shape. Not a proper monster's claw mark. There was a faint smell of decay in the air as well. Their living room table had been crashed into by something heavy, demolishing it. Sans was chubby but not that heavy. He would've had to be thrown extremely hard for his body to be able to destroy it. And a force that big would've … dusted him.

And thankfully, there was no dust here.

 _There had been no dust where Blue disappeared as well._

"Shut up. Concentrate" he murmured to himself. The shaking in his hands was growing.

 _He's alright. He's ok. He will be found. He will NOT hold a funeral for his own brother._

He looked around again, rage and anxiety clouding the edges of his vision.

 _Concentrate. Where… Where is the exit point?_

A hastily covered window gave him the answer. Something had crashed through it. Again, it had had to be something really heavy and powerful to do such destruction. His home windows were as secure as possible. He paid a lot of gold for them.

He pushed aside the covering with one hand and looked at the destroyed tree branches just outside the window. There were no footprints even though it hadn't snowed yet. How could something that powerful not leave a trail?

Especially if they had been carrying something.

He turned around to leave and meet up with the Patrol looking for his brother when he noticed the backpack leaning against the sofa. An old thing that Red used to carry when they went camping in the Forest. Fell hadn't seen it in years.

He opened the backpack and saw some food and extra clothes packed in there. As well as some assorted camping equipment.

 _Had Sans planned to leave?_

 _Why?_

His brother had never liked being a Sentry. Never. He'd been embarrassed when he was dismissed but, Fell was also sure he was also relieved to be done with that obligation.

 _Hadn't he been?_

Fell threw the backpack onto the couch. NO. This would not end the same way.

He would not allow it.

As the readings counted down to zero he felt his Love slowly increase

Such a weird, unwelcome feeling.

He had loved this one as much as the last one. Not at all. Yet, he still felt regret when their numbers finally became a flat line on the monitor. Part of him still wondered about this one's loved ones. If he would be missed.

He held his breath by habit as he waited for the results.

 _Perhaps this was the last one._

The machine churned and beeped. The screen coming alive with the same damned words as always:

MORE DATA NEEDED.

He took a deep breath in biting back the expletive he so dearly wanted to shout. Processing took about a week. Some of them had taken more time and some less. During this waiting period, he entertained himself reading up on things, checking equipment he only half understood and trying to get some sleep. But none of that worked. He was always plagued by the sounds and memories of begging and questions he had stopped caring to answer. It didn't matter, if he did or not, they wouldn't remember anyway.

And forgiveness was impossible.

He usually avoided having more than one in the ship. It helped avoid even more confusion and drama. Most of them weren't even remotely aware that alternates of themselves existed. Meeting another one of you was bad enough. Watching each other slowly die was even worse.

Still, he wished Alphys could've created more than one fully functional chamber. She had barely had gotten the first one working. Her computer notes contained some mumbo jumbo explanation of "energy allowances not being sufficient" and "unexpected temporal load" and blah, blah, blah blah.

The whole thing just made his head hurt. He had been lucky to understand as much as he did on how to use the machine.

Grunting with exasperation, he switched the thing off so it could recharge for the next subject.

He heard sobbing behind him and reflexively closed his eyes. His anger replaced by weird mix of guilt and annoyance. He knew that the young one had been trying to stifle it for awhile now. Seeing that soul finally shatter into its final pieces had been the last nail in the coffin, he guessed.

"Stop that" he grumbled without turning around. "What do you care? You never even talked to him. Trust me, it's better if you don't think about it"

Banging. Fists against glass.

Their voice was muffled by the same glass they were hitting, so he couldn't quite make out what they were saying. It was an easy enough guess though. It was a several days old argument by now.

He turned around to face his next potential subject. He had taken him early. The opportunity had been too perfect to ignore. The readings had been strong. _Promising._ If it hadn't been for the one already in the Chamber, he would've processed him already.

But he had made a mistake.

They had talked.

He was used to shock and surprise, but this one had just greeted him. He had been curious, but not afraid nor confused. In fact, he had been a little overexcited to see him come up to him.

Exhaustion. That had to be it. It clouded his judgment. _Stars, when was the last time he had gotten any real sleep?_

He usually let his gasters do the capturing. But this time …. maybe the place reminded him of what his own world used to be. Maybe it had been the fact that this target had been working on a very interesting looking puzzle at the time.

So they had talked.

He had almost walked away. Left this world alone.

Then he remembered his machine's readings.

 _What if..._

He had put him in the spare chamber with the intention of keeping him asleep until his turn came. He followed this plan for the first couple of days, but he often found himself peeking in. Wondering. Fighting the temptation to wake him. He couldn't quite put a bony finger on what exactly, but something about this one bothered him.

 _Like they all did._ He looked like his brother.

But unlike the others, he didn't -feel- like him.

He should've stuck to his plan. It was in place for everybody's good. If he put them to sleep first, there was a chance that they would never wake up again, not even after the processing started. They just went quietly. The ones that did wake up, suffered. There was nothing he could do after the machine started its deadly goal. He couldn't even give them unconsciousness.

The chamber could not be opened once it started working. He was glad for the thick glass that muffled their cries. He only stayed in the room out of obligation, at least that way they wouldn't be alone.

Eventually, they would go quiet and stare at nothing. Their minds taken. The machine would then keep them alive until the very last moment. Their soul the last part of them to be deconstructed and analyzed.

If only they would only understand that it was all necessary, to save the universes from his own brother's arrogance.

If only…

He looked at the sobbing young skeleton. Could he afford to spare him? Maybe this one would understand.

Maybe…

Forgive him.


End file.
